Controlled blending of biodiesel into distillate streams

ABSTRACT

Methods are provided for accurately blending biodiesel into distillate streams to achieve a pre-determined percentage of biodiesel in the distillate, applicable to wild-type distillate streams as well as distillate streams that already contain some percentage of biodiesel.

FIELD OF THE INVENTION

The present invention relates to biodiesel, and to methods formaximizing the utilization of biodiesel fuels in distillates such asdiesel fuel and fuel oil.

BACKGROUND OF THE INVENTION

Petroleum pipelines are a critical element of world-wide fueldistribution networks, delivering refined fuel products from ports andrefineries to storage facilities in various geographic locations.Through an intricate network of coordinated deliveries from multiplesources, batches of varying grades and types of fuel travel throughthese pipelines to predetermined locations. Tank farms are used to storefuel delivered through these pipelines, and to distribute the fuel toother tank farms and ultimately to tanker trucks that deliver the fuelto end user outlets such as retail fuel stations and airports. Petroleumproducts are typically dispensed to tanker trucks in what is known as arack, which usually comprises several outlet ports to which differentgasoline and diesel transports may be coupled.

The United States Environmental Protection Agency (EPA) and otherregulatory authorities have promulgated regulations and fuel standardsthat mandate a certain amount of biodiesel that must be blended withdiesel each year. These regulations generally apply in aggregate for theyear. However, due to the effects of cold temperature on the dieselproperties, most biodiesel blending occurs in the warmest months of coldclimate geographic areas. State and local regulations also establishlabeling requirements for diesel based on the amount of biodieselblended with the diesel that vary by the region in which the diesel willbe dispensed and sold.

Biodiesel is often blended with diesel at tank farms, racks, and retaillocations. This blending can occur in-line, so that biodiesel is addeddirectly to a line that is transporting the diesel to a terminal orin-line delivery to a tank truck. Alternatively, blending can occur inbatches, as when biodiesel is added to a storage tank or tank truck. Theaddition of biodiesel to a storage tank in a separate batch from thediesel is referred to as “tank blending.” The addition of biodiesel to atank truck in a separate batch from the diesel is referred to as “splashblending.”

As explained by Kram J, No need to splash, BIODIESEL MAGAZINE (Jan. 17,2008), blending of biodiesel into diesel fuel is typically governed bypercentage limits. Thus, when blending on a pipeline into a wild dieselstream to which no biodiesel has been added, a pipeline operator simplyblends biodiesel to the target percentage, using a process known as“ratio blending.” An exemplary system for carrying out this ratioblending is the Multi-Stream Blender™ by Honeywell Enraf Americas Inc.However, this type of “ratio blending” is not possible when biodieselhas already been added to the stream, because ratio blending to a mixedbiodiesel/diesel stream could cause the stream to exceed its biodieselpercentage target.

The same holds true for splash building, which is commonly based on thevolumes or weights of diesel and biodiesel added to a tanker truck.Using the volume method, a truck will receive a measured volume ofdiesel, and then add a measured volume of biodiesel to complete thetarget blend. Using the weight method, a truck is often weighed on ascale, filled, weighed again and the difference between the weights isthe amount of biodiesel that's been added. To make a blend such as B5that contains 5% biodiesel, a proportional volume or weight of biodieselis splash blended with the petroleum diesel. Once again, this processcannot be used if the diesel already contains biodiesel, because of thepotential for exceeding the percentage limit on biodiesel in the blend.

Biodiesel blending can be especially challenging on the multi-productpipelines that carry the vast majority of fuels from ports andrefineries, because of the potential for mixing biodiesel withincompatible fuels, particularly aviation turbine fuels. Becausebiodiesel contamination of aviation turbine fuel is limited to almostundetectable levels in ASTM specification D1655, common carrierpipelines have responded by banning biodiesel-containing distillate onmost of their line segments, thus relegating biodiesel blending tosplash blending or tank blending processes individually at the tankfarms and retail locations at the end of the pipelines.

Therefore, it is an object of the present invention to provide moreversatile methods for blending biodiesel into diesel streams and otherfuel streams where biodiesel is permitted, that can be used regardlessof the biodiesel content of the stream, to achieve target concentrationsof biodiesel in the blend.

Another object is to provide automated methods for monitoring thebiodiesel content of a diesel or other fuel stream, and for controllingthe blending of biodiesel into the diesel or other fuel stream based onthe biodiesel content based on real-time biodiesel percentagemeasurements.

Another object of the present invention is to facilitate biodieselblending into diesel and other fuel streams to achieve defined biodiesellimits in the diesel or other fuel.

Still another object of the present invention is to facilitate blendingof biodiesel into distillate streams along multi-product fuel pipelines,including pipelines that carry aviation turbine fuel.

SUMMARY OF INVENTION

Thus, in a first principal embodiment the invention provides anautomated method of blending biodiesel into a distillate stream toachieve a target biodiesel content comprising: (a) providing adistillate stream having a distillate stream flow rate; (b) providing asupply of biodiesel having a biodiesel stream flow rate in liquidcommunication with said distillate stream, separated from saiddistillate stream by a regulating valve that is under the control of acentral processing unit; (c) providing a target biodiesel content forsaid distillate stream; (d) periodically measuring an actual biodieselcontent in said distillate stream, upstream and/or downstream of saidregulating valve; (e) periodically transmitting said actual biodieselcontent to said central processing unit; (f) periodically calculating insaid central processing unit a target blending rate at which biodieselcan be blended into said distillate stream to achieve the targetbiodiesel content; and (g) modulating said regulating valve to blendbiodiesel into said distillate stream at said target blending rate.

In a second principal embodiment the invention provides an automatedsystem for blending biodiesel into a distillate stream to achieve atarget biodiesel content comprising: (a) a distillate stream having adistillate stream flow rate; (b) a supply of biodiesel in liquidcommunication with said distillate stream, separated from saiddistillate stream by a regulating valve that is under the control of acentral processing unit; (c) a target biodiesel content for saiddistillate stream accessible by said central processing unit; (d) ananalyzer for measuring an actual biodiesel content of said distillatestream, upstream and/or downstream of said valve; (e) means fortransmitting said actual biodiesel content to said central processingunit; (f) means for calculating in said central processing unit a targetrate at which biodiesel can be blended into said distillate stream toachieve the target biodiesel content; and (g) means for periodicallymodulating said regulating valve to blend biodiesel into said distillatestream at said target blending rate.

In a third principal embodiment an automated method of blendingbiodiesel into a distillate stream so as not to exceed a maximumbiodiesel content comprising: (a) providing a distillate stream having adistillate stream flow rate; (b) providing a supply of biodiesel havinga biodiesel stream flow rate in liquid communication with saiddistillate stream, separated from said distillate stream by a regulatingvalve that is under the control of a central processing unit; (c)providing a maximum biodiesel content for said distillate stream; (d)periodically measuring an actual biodiesel content in said distillatestream, upstream and/or downstream of said regulating valve; (e)periodically transmitting said actual biodiesel content to said centralprocessing unit; (f) periodically calculating in said central processingunit a maximum flow rate at which biodiesel can be blended into saiddistillate stream so as not to exceed the maximum biodiesel content; and(g) modulating said regulating valve to blend biodiesel into saiddistillate stream at or below said maximum blending rate.

In a fourth principal embodiment the invention provides an automatedsystem for blending biodiesel into a distillate stream so as not toexceed a maximum biodiesel content comprising: (a) a distillate streamhaving a distillate stream flow rate; (b) a supply of biodiesel inliquid communication with said distillate stream, separated from saiddistillate stream by a regulating valve that is under the control of acentral processing unit; (c) a maximum biodiesel content for saiddistillate stream accessible by said central processing unit; (d) ananalyzer for measuring an actual biodiesel content of said distillatestream, upstream and/or downstream of said valve; (e) means fortransmitting said actual biodiesel content to said central processingunit; (f) means for calculating in said central processing unit amaximum rate at which biodiesel can be blended into said distillatestream so as not to exceed the target biodiesel content; and (g) meansfor periodically modulating said regulating valve to blend biodieselinto said distillate stream at or below said maximum blending rate.

Additional advantages of the invention are set forth in part in thedescription which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. Theadvantages of the invention will be realized and attained by means ofthe elements and combinations particularly pointed out in the appendedclaims. It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory only and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments of theinvention and together with the description serve to explain theprinciples of the invention.

FIG. 1 is a schematic drawing of the layout of a representativebiodiesel blending system.

DETAILED DESCRIPTION Definitions and Use of Terms

As used in this specification and in the claims which follow, thesingular forms “a,” “an” and “the” include plural referents unless thecontext clearly dictates otherwise.

As used in this specification and in the claims which follow, the word“comprise” and variations of the word, such as “comprising” and“comprises,” means “including but not limited to,” and is not intendedto exclude, for example, other additives, components, integers or steps.When an element is described as comprising a plurality of components,steps or conditions, it will be understood that the element can also bedescribed as comprising any combination of such plurality, or“consisting of” or “consisting essentially of” the plurality orcombination of components, steps or conditions.

Throughout the patent application, wherever an analysis of petroleum orbiodiesel is disclosed according to a particular standard, such as anEPA regulation or a standard promulgated by the American Society forTesting and Materials (“ASTM”), it will be understood that such standardis the standard in effect on Jan. 1, 2017. However, it will also beunderstood that a product that satisfies a particular ASTM standard neednot have been tested according to that standard. Thus, for example,biodiesel defined by the Jan. 1, 2017, version of ASTM Standard D6751covers biodiesel that meets this standard, regardless of whether it wastested for actual compliance with this standard.

When ranges are given by specifying the lower end of a range separatelyfrom the upper end of the range, or specifying particular numericalvalues, it will be understood that a separate range can be defined byselectively combining any of the lower end variables, upper endvariables, and particular numerical values that is mathematicallypossible. In like manner, when a range is defined as spanning from oneendpoint to another, the range will be understood also to encompass aspan between and excluding the two endpoints.

“Biodiesel” refers generally to a fuel source comprised of mono-alkylesters of long chain fatty acids derived from vegetable oils or animalfats that has been chemically processed to remove glycerin. Themono-alkyl esters are preferably comprised predominantly (i.e. greaterthan 80%, 90%, 95%, or 98%) or essentially of mono-methyl-esters of longchain fatty acids. A particularly preferred biodiesel for use in thecurrent invention is referred to as B100, and is defined according toASTM Standard D6751. The biodiesel can be Grade No. 1-B S15 (A specialpurpose biodiesel blendstock intended for use in middle distillate fuelapplications which can be sensitive to the presence of partially reactedglycerides, including those applications requiring good low temperatureoperability, and also requiring a fuel blend component with 15 ppmsulfur (maximum)), Grade No. 1-B S500 (A special purpose biodieselblendstock intended for use in middle distillate fuel applications whichcan be sensitive to the presence of partially reacted glycerides,including those applications requiring good low temperature operability,and also requiring a fuel blend component with 500 ppm sulfur(maximum)), Grade No. 2-B S15 (A general purpose biodiesel blendstockintended for use in middle distillate fuel applications that require afuel blend component with 15 ppm sulfur (maximum)), or Grade No. 2-BS500 (A general purpose biodiesel blendstock intended for use in middledistillate fuel applications that require a fuel blend component with500 ppm sulfur (maximum)). A preferred biodiesel for use in the presentinvention is B100 (i.e. 100% biodiesel), although biodiesel which hasalready been blended with diesel, such as B99, can also be used as thebiodiesel.

The term “distillate” as used herein refers to those fuels commonlyreferred to as “middle distillates” in the petroleum industry, with theexception of aviation turbine fuel. “Middle distillates” is a termcommonly assigned to petroleum products obtained in the “middle” boilingrange from about 180° C.-360° C. during the process of crude oildistillation. They are also called middle distillates because theproducts are removed at mid-height in the distillation tower during themulti-stage process of thermal separation. A middle distillate is aclear, colorless to light yellow, combustible liquid. It typically hasbetween eleven and eighteen carbon atoms, a density of not more than0.876 kg/1 at 15° C., and a flashpoint above 38° C. Middle distillatesprimarily include diesel fuel, marine fuels, non-aviation turbine fuel,heating oil, and kerosene.

The term “diesel fuel” as used herein means a petroleum-derived liquidfuel used in diesel engines, whose fuel ignition takes place without anyspark as a result of compression of the inlet air mixture and theninjection of fuel. Diesel fuel is a mixture of hydrocarbons with boilingpoints in the range of 200 to 380° C. Diesel fuel utilized in thepresent invention preferably satisfies the testing requirementsspecified in ASTM D975. The diesel fuel can be Grade No. 1-D S15 (aspecial-purpose, light middle distillate fuel for use in diesel engineapplications requiring a fuel with 15 ppm sulfur (maximum) and highervolatility than that provided by Grade No. 2-D S15 fuel), Grade No. 1-DS500 (a special-purpose, light middle distillate fuel for use in dieselengine applications requiring a fuel with 500 ppm sulfur (maximum) andhigher volatility than that provided by Grade No. 2-D S500 fuel), GradeNo. 1-D S5000 (a special-purpose, light middle distillate fuel for usein diesel engine applications requiring a fuel with 5000 ppm sulfur(maximum) and higher volatility than that provided by Grade No. 2-DS5000 fuels), Grade No. 2-D S15 (a general purpose, middle distillatefuel for use in diesel engine applications requiring a fuel with 15 ppmsulfur (maximum). It is especially suitable for use in applications withconditions of varying speed and load), Grade No. 2-D S500 (ageneral-purpose, middle distillate fuel for use in diesel engineapplications requiring a fuel with 500 ppm sulfur (maximum). It isespecially suitable for use in applications with conditions of varyingspeed and load), Grade No. 2-D S5000 (a general-purpose, middledistillate fuel for use in diesel engine applications requiring a fuelwith 5000 ppm sulfur (maximum), especially in conditions of varyingspeed and load), or Grade No. 4-D (a heavy distillate fuel, or a blendof distillate and residual oil, for use in low- and medium-speed dieselengines in applications involving predominantly constant speed andload).

The term “heating oil” refers to fuel oil intended for use in varioustypes of fuel-oil-burning equipment under various climatic and operatingconditions. Heating oil preferably satisfies the specificationsdescribed in ASTM D396, and includes Grades No. 1 S5000, No. 1 S500, No.1 S15, No. 2 S5000, No. 2 S500, and No. 2 S15 (middle distillate fuelsfor use in domestic and small industrial burners). Grades No. 1 S5000,No. 1 S500, and No. 1 S15 are particularly adapted to vaporizing typeburners or where storage conditions require low pour point fuel).Heating oil also includes Grades B6—B20 S5000, B6—B20 S500, and B6—B20S15 (middle distillate fuel/biodiesel blends for use in domestic andsmall industrial burners), Grades No. 4 (Light) and No. 4 (heavydistillate fuels or middle distillate/residual fuel blends used incommercial/industrial burners equipped for this viscosity range), GradesNo. 5 (Light), No. 5 (Heavy), and No. 6 (residual fuels of increasingviscosity and boiling range, used in industrial burners). Kerosene alsohas its commonly understood meaning, although it will preferably satisfyD975 1D, S15 and 5500 for motor fuel application, and ASTM D3699 forburner applications (although biodiesel blending is not commonlypracticed with burner kerosene).

The terms “distillate,” “diesel,” “marine fuel,” “heating oil,”“kerosene,” and “non-aviation turbine fuel” when used herein refer tosuch products before and after blending with biodiesel. Other morespecific terms can be used to refer to distillates that have beenblended with biodiesel, such as “blended distillate” or“biodiesel/distillate blend.” Biodiesel/diesel blends preferably satisfythe ASTM D975 specifications for “diesel” provided herein when thepercentage of biodiesel in the blend does not exceed 5 vol %. A 5 vol %biodiesel/diesel blend is commonly called B5 diesel or B5 biodieselblend. In one embodiment, the biodiesel is blended into the dieselstream up to 5 vol %, although any blend percentage can be adopted basedon the needs of the downstream user. In another embodiment, the blendedstream comprises from 6 vol % to 20 vol % biodiesel (B6 to B20), and theblended product satisfies the testing requirements specified in ASTMD7467.

“Calculation” means the use of a mathematical algorithm to determine avalue, and may be by a programmed software, a hardwired algorithm, ormental means.

“Density” means the density of a substance as a function of mass perunit volume. The density can be reported directly, in terms of mass perunit volume, or indirectly using measures such as specific gravity.

“Distillate stream” means a stream of distillate that is flowing througha pipeline or other conduit.

“Flow rate” means the volume of a fluid that flows past a given pointover a given period of time.

“Fluid communication” refers to the linkage of a pipeline to a source ofa fluid. Optionally the linkage may be through a channel that can beclosed or whose flow may be modulated as by a valve. The linkage may beby any of the following: a door or window on the side of the pipeline; abranching pipe in the pipeline; an injection-facilitating fixture in ajoint of the pipeline; a smaller secondary pipe that extends into theinterior of the pipeline; or any other means that permits a fluid toflow into the pipeline. Optionally the flow may be constant, variable,or intermittent. In certain preferred embodiments of the invention thefluid flow into the pipeline by means of this linkage is capable ofbeing modulated or stopped.

“Information processing unit” and “IPU” means a computational unit thatis useful for at least one of accessing, receiving, processing,distributing and storing data. The IPU may receive data either passivelyor by affirmatively soliciting or searching for data on a separateinformation system. When an IPU is modified by the term “an,” it will beunderstood that the invention contemplates that one or more IPU's mayperform the function described for the IPU.

“Informational database” and “IDB” means an organized collection ofinformation. As used herein the term includes spreadsheets, look-uptables, and dedicated database applications, and includes bothelectronic and hard copy databases. When an IDB is modified by the term“an,” it will be understood that the invention contemplates that one ormore IDB's may perform the function described for the IDB.

“Blending” as used with respect to a pipeline means insertion of a fluidinto a pipeline.

“Actual blending rate” means the actual—as opposed to predicted—flowrate of the fluid into the pipeline during a blending operation.

“Biodiesel content” means biodiesel measured as a percentage of totalhydrocarbon volume, preferably rounded to the nearest 1%.

“Obtaining” data or other information means acquiring such information.In some preferred embodiments information is obtained by making physicalmeasurements. In other preferred embodiments information is obtained byreceiving measurement data from a separate source. In still otherpreferred embodiments information is obtained from an in-house look-uptable or databank. The term obtaining is to be understood in itsbroadest sense. The information obtained should also be understood in abroad sense, and may include values for physical parameters, regulatoryguidelines, correlation tables for fuel properties, availability ofdistillate or biodiesel, and other types of information.

“Pooled supply” means a reservoir or otherwise collected reserve of afluid intended for use in mixing. The term includes pooled supplies forany of the following: distillates, biodiesel, hydrocarbons, and otherfuel components.

“Pre-defined limit” means a predetermined boundary value for aparameter, where the source of the boundary value is a regulation, acompany's policy, or an operator's professional judgment. The term“pre-defined limit” is used herein particularly with respect tobiodiesel content in distillate fuels.

“Tank farm” means any facility that contains a number of large storagetanks for petroleum products, typically including loading racks fromwhich tanker trucks are filled. The tanks may contain one or more typesand grades of gasoline, including reformulated gasoline, and may alsocontain in pure form or in composite fluids, biodiesel, distillates orother petroleum products.

“Target rate” means a desired rate of fluid flow.

“Variable rate” means a rate of fluid flow that changes over time.

PRINCIPAL EMBODIMENTS

The invention is described herein in terms of principal embodiments andsubembodiments. It will be understood that each of the subembodimentscan modify any of the principal embodiments, unless such modification islogically inconsistent or expressly disallowed in this document. It willbe further understood that the principal embodiments can be combined inany manner, and that the subembodiments can be combined in any manner tofurther modify any of the principal embodiments, unless such combinationis logically inconsistent or expressly disallowed in this document.

In a first principal embodiment the invention provides an automatedmethod of blending biodiesel into a distillate stream to achieve atarget biodiesel content comprising: (a) providing a distillate streamhaving a distillate stream flow rate; (b) providing a supply ofbiodiesel having a biodiesel stream flow rate in liquid communicationwith said distillate stream, separated from said distillate stream by aregulating valve that is under the control of a central processing unit;(c) providing a target biodiesel content for said distillate stream; (d)periodically measuring an actual biodiesel content in said distillatestream, upstream and/or downstream of said regulating valve; (e)periodically transmitting said actual biodiesel content to said centralprocessing unit; (f) periodically calculating in said central processingunit a target blending rate at which biodiesel can be blended into saiddistillate stream to achieve the target biodiesel content; and (g)modulating said regulating valve to blend biodiesel into said distillatestream at said target blending rate.

In a second principal embodiment the invention provides an automatedsystem for blending biodiesel into a distillate stream to achieve atarget biodiesel content comprising: (a) a distillate stream having adistillate stream flow rate; (b) a supply of biodiesel in liquidcommunication with said distillate stream, separated from saiddistillate stream by a regulating valve that is under the control of acentral processing unit; (c) a target biodiesel content for saiddistillate stream accessible by said central processing unit; (d) ananalyzer for measuring an actual biodiesel content of said distillatestream, upstream and/or downstream of said valve; (e) means fortransmitting said actual biodiesel content to said central processingunit; (f) means for calculating in said central processing unit a targetrate at which biodiesel can be blended into said distillate stream toachieve the target biodiesel content; and (g) means for periodicallymodulating said regulating valve to blend biodiesel into said distillatestream at said target blending rate.

In a third principal embodiment an automated method of blendingbiodiesel into a distillate stream so as not to exceed a maximumbiodiesel content comprising: (a) providing a distillate stream having adistillate stream flow rate; (b) providing a supply of biodiesel havinga biodiesel stream flow rate in liquid communication with saiddistillate stream, separated from said distillate stream by a regulatingvalve that is under the control of a central processing unit; (c)providing a maximum biodiesel content for said distillate stream; (d)periodically measuring an actual biodiesel content in said distillatestream, upstream and/or downstream of said regulating valve; (e)periodically transmitting said actual biodiesel content to said centralprocessing unit; (f) periodically calculating in said central processingunit a maximum flow rate at which biodiesel can be blended into saiddistillate stream so as not to exceed the maximum biodiesel content; and(g) modulating said regulating valve to blend biodiesel into saiddistillate stream at or below said maximum blending rate.

In a fourth principal embodiment the invention provides an automatedsystem for blending biodiesel into a distillate stream so as not toexceed a maximum biodiesel content comprising: (a) a distillate streamhaving a distillate stream flow rate; (b) a supply of biodiesel inliquid communication with said distillate stream, separated from saiddistillate stream by a regulating valve that is under the control of acentral processing unit; (c) a maximum biodiesel content for saiddistillate stream accessible by said central processing unit; (d) ananalyzer for measuring an actual biodiesel content of said distillatestream, upstream and/or downstream of said valve; (e) means fortransmitting said actual biodiesel content to said central processingunit; (f) means for calculating in said central processing unit amaximum rate at which biodiesel can be blended into said distillatestream so as not to exceed the target biodiesel content; and (g) meansfor periodically modulating said regulating valve to blend biodieselinto said distillate stream at or below said maximum blending rate.

Subembodiments

The measurement of biodiesel in the distillate stream, whether performedupstream or downstream of the biodiesel addition point on the distillateline, can be performed using any automated analytical method includingnear infra-red spectroscopy, mid infra-red spectroscopy, gaschromatography or mass spectroscopy. In a preferred subembodiment, thebiodiesel content is measured using mid infra-red spectroscopy,according to ASTM D7371, EN14078, or ASTM D7861. Mid Infrared (400-4000cm⁻¹) was selected for these standards because it covers the fingerprintband of IR response for biodiesel, including 1745 cm⁻¹ for the C═O bond,which is not found in diesel. However, in an even more preferredembodiment, the biodiesel content is measured by Near Infrared(4000-12,500 cm⁻¹) Spectroscopy. Near Infrared Spectroscopy is based onthe overtones and combinations of vibrational frequencies of thefingerprint bonds of biodiesel.

In a particularly preferred subembodiment, the mid or near infra-redspectroscopy is performed in a machine calibrated to measure biodieselcontent in Grade No. 1-D S15 diesel fuel, Grade No. 2-D S15 diesel fuel,Grade No. 1-D S500 diesel fuel, Grade No. 2-D S500 diesel, Grade No. 1-DS5000 diesel fuel, Grade No. 2-D S5000 diesel fuel, Grade No. 4-D dieselfuel, or a combination of these grades, or all of these grades.

Near IR analytical machines which can be adapted for automatedmeasurements of biodiesel content include the FTPA 2000—HP360 FTIR FieldMountable Single Process Analyzer™ by ABB Analytical Measurement,Quebec, Canada, the near infra-red Biodiesel Analyzer™ by LT Industries,Inc, Gaithersburg, Md., and the Matrix-F FT-NIR Spectrometer™ by BrukerCorporation, Billerica, Mass.

The biodiesel blending rate can be calculated based on biodieselmeasurements taken upstream of the biodiesel addition point according tothe following formula:

(BD_(FR))=(D_(FR)(target %−D_(BD %)))/(1−target %)

where:

-   -   BD_(FR)=Biodiesel flow rate    -   D_(FR)=Distillate flow rate upstream of addition point    -   D_(BD %)=Distillate biodiesel % upstream of addition point

Alternatively, the biodiesel blending rate can be calculated using afeedback control process based on biodiesel measurements takendownstream of the biodiesel addition point. In a preferred embodiment,however, biodiesel measurements are taken upstream and downstream of thebiodiesel addition point; the upstream measurement is used to determinethe biodiesel blending rate; and the downstream measurement is used toconfirm the content of the blended stream. In this embodiment, a signalassociated with the actual downstream biodiesel content is preferablygenerated and communicated to an IPU to indicate whether the actualdownstream biodiesel content has achieved the target biodiesel contentat a particular time point.

The method is particularly well adapted to the generation of recordswhich document the rate of addition or amount of biodiesel in thedistillate line. Thus, in one subembodiment the measuring step occursupstream of the biodiesel addition point, and the method furthercomprises measuring an actual downstream biodiesel content in saiddistillate stream, associating in an information database said resultingactual downstream biodiesel content with a time point to provideassociated temporal data; recording said associated temporal data in aninformational database; and periodically repeating the process. In oneparticular subembodiment, the time point is received in said informationdatabase from an external source.

The blending will commonly occur along a variable fuel transmission pipe(a/k/a multi-product pipeline) that transmits a plurality of differentpetroleum types, including gasoline (regular and premium), diesel fuel(various grades), heating oil, and aviation fuel. In this embodiment,the pipeline will eventually intersect with a line that is dedicated tothe flow of distillate, and that intersects with the pipeline, or a pipein fluid communication with the pipeline, at a distillate fueldiversionary valve. Alternatively, the blending can occur inside a pipethat is dedicated to the transmission of the distillate. For example,the blending can occur in a single fuel transmission pipe destined for adistillate fuel storage tank or a single fuel transmission pipe destinedfor a distillate fuel tanker truck.

In another subembodiment, the methods and systems of the currentinvention are adapted to ensure that biodiesel is not inadvertentlyadded to fuel types other than distillates. Thus, in one subembodiment,the distillate stream comprises a batch of distillate fuel preceded andsucceeded by batches of non-distillate fuel, further comprising ceasingany biodiesel blending as said non-distillate fuel passes said valve.

In another subembodiment, the distillate stream comprises a batch ofdistillate fuel preceded and succeeded by batches of non-distillatefuel, further comprising monitoring said distillate stream for theidentity of said batch at said valve, and only blending biodiesel intosaid distillate stream when said batch of distillate fuel is passing bysaid valve. A particularly preferred method of determining the identityof the fuel in the pipeline is density, and such method can be performedas part of the blending operation, or density measurements furnishedfrom an external source.

In one particular subembodiment, the identity of the fuel inside thepipeline is determined by measuring the density of the stream, furthercomprising providing a range of densities associated with distillatefuel, and only blending biodiesel into said distillate stream when saidstream falls within the range of specific gravities associated withdistillate fuel. In still further subembodiments, the identity of thefuel inside the pipeline is determined based on a batch code associatedwith the stream that is flowing past the valve. In this subembodiment,the batch code of the fuel traveling past the valve is commonlyfurnished by an external source, and associated with a fuel typerecorded in a database maintained in the systems and methods of thepresent invention.

In another subembodiment, the distillate stream comprises a batch ofdiesel fuel preceded or succeeded by a batch of a fuel which isincompatible with biodiesel such as aviation turbine fuel. Variousstrategies can be used to ensure that biodiesel does not contaminate theaviation turbine fuel. For example, the user of the system mightdesignate a front or end segment of the distillate stream as “blendfree,” thereby creating a buffer between the distillate with whichbiodiesel has been mixed and the interface between the distillate andthe aviation fuel. Thus, in one subembodiment the methods of the currentinvention further comprise establishing a buffer of distillate fuel atan interface between said diesel fuel and said aviation fuel, andceasing biodiesel blending in said buffer. The buffer can be based ontime or volume of fluid flow, but will always be defined to preclude anymixing of biodiesel into the abutting stream with which the biodiesel isincompatible.

Another strategy for preventing contamination is to insert a physicalbuffer between the distillate and aviation fuel streams, and to assign aseparate batch code to the buffer to monitor its progress past theregulating valve. Thus, in another subembodiment, the distillate streamis preceded or succeeded by an aviation turbine fuel stream and a bufferstream interposed between said distillate stream and said aviationturbine fuel stream, further comprising (a) providing a distillatestream batch code for said distillate stream; (b) associating saiddistillate stream batch code with a front end and a tail end of saiddistillate stream on said central processing unit; (c) providing abuffer stream batch code for said buffer stream; (d) associating saidbuffer stream batch code with a front end and a tail end of said bufferstream on said central processing unit; (e) monitoring the progress ofsaid distillate stream and said buffer stream on said central processingunit relative to said regulating valve; and (f) executing programmablelogic on said central processing unit based on the progress of saiddistillate and buffer streams to prevent blending of biodiesel into saidbuffer stream as the buffer stream flows past said regulating valve. Theregulating valve can be under the control of the same central processingunit as the central processing unit on which monitoring step (e) andexecuting step (f) are performed, or a different central processingunit. When the central processing units are different, the method willfurther comprise the first central processing unit signaling theregulating valve to stop blending into the distillate stream in responseto a corresponding signal from the second central processing unit to thefirst central processing unit.

Still another method of preventing contamination of the aviation fuelstream by the biodiesel involves monitoring for indicia of aviationturbine fuel, and preventing blending when the stream passing theregulating valve has physical properties corresponding to those indicia.Thus, in still another subembodiment, wherein the distillate stream ispreceded or succeeded by an aviation turbine fuel stream, the methodfurther comprises: (a) providing an indicia of aviation turbine fuelcorresponding to a physical property of aviation turbine fuel,accessible by the central processing unit; (b) monitoring the distillatestream for the physical property, and transmitting the physical propertyto the central processing unit; and (c) executing programmable logic onsaid central processing unit to: (i) compare the physical property withthe indicia, and (ii) communicate to the regulating valve to stopblending biodiesel when the physical property matches the indicia.Preferred indicia for this subembodiment include density, pour point andsulfur content, and combinations thereof.

The flow rate of distillate can remain unchanged over time or it canvary. When the rate varies, measurements will preferably be taken of theflow rate in real time, and the biodiesel addition rate calculated basedon the actual flow rate of the distillate stream.

The rate at which the biodiesel is added to the distillate is preferablydetermined by the relative pressures of the biodiesel and distillatestreams at the point of addition, with the biodiesel stream pressurehigher than the distillate stream pressure. The pressure of thebiodiesel stream is preferably under the control of a coordinated pumpand valve system, as shown in greater detail in the figure hereto.

Chemometrics

“Chemometrics” is a term applied to the generic discipline of usingcomputers and mathematics to derive meaningful chemical information fromsamples of varying complexity. (Workman, J. J., Jr (2008) NIRspectroscopy calibration basic. In: Burns, D. A. and Ciurczak, E. W.(eds), Handbook of Near-Infrared Analysis, 3rd edn. CRC Press, BocaRaton, Fla.) In chemometrics, a computer is tasked with interpreting NIRspectra from a plurality of samples using a variety of multivariatemathematical techniques. These techniques are used to produce amathematical calibration model.

In routine NIR analysis, the spectra should be pretreated to enhanceinformative signals of the interested components and reduceuninformative signals as much as possible. (Pantoja P A et al.,Application of Near-Infrared Spectroscopy to the Characterization ofPetroleum, in Analytical Characterization Methods for Crude Oil andRelated Products, First Edition. Edited by Ashutosh K. Shukla. Published2018 by John Wiley & Sons Ltd.) Smoothing, multiplicative scattercorrection, mean centering, and Savitzky-Golay derivation are commonlyapplied to pretreat the spectra before modeling in order to remove thescattering effect created by diffuse reflectance and to decreasebaseline shift, overlapping peak, and other detrimental effects on thesignal-to-noise ratio. (Boysworth, M. K. and Booksh, K. S. (2008)Aspects of multivariate calibration applied to near-infraredspectroscopy. In: Burns, D. A. and Ciurczak, E. W. (eds), Handbook ofNear-Infrared Analysis, 3rd edn. CRC Press, Boca Raton, Fla.)

NIR spectra are ultimately calibrated to relate the observed spectra, ina predictive manner, to a property of interest. With calibration it ispossible to predict relevant physicochemical properties of an unknownhydrocarbon that compare accurately with reference information on theseproperties. In the process of this invention, the reference informationis generated from pipeline samples taken simultaneously with spectralinformation on the pipeline to generate a chemometric dataset. The maincalibration methods, as described by López-Gejo et al., 2008, includeprincipal component analysis (PCA), partial least squares (PLS)regression, and artificial neural networks (ANNs). (López-Gejo, J.,Pantoja, P. A., Falla, F. S., et al. (2008) Electronical and vibrationalspectroscopy. In: Petroleum Science Research Progress, Publisher, Inc.,187-233)

Thus, in other methods and systems of the present invention, one or morephysical property values are obtained by generating a spectral responseof said distillate stream using absorption spectroscopy with a nearinfrared analyzer, and comparing said spectral response to a chemometricdataset specific for said physical property value in said distillatestream.

In further methods and systems of the present invention, the chemometricdataset is built by taking two or more samples of said distillate streamfrom a pipeline; measuring said physical property of the samplesoffline; simultaneously with taking the two or more samples, obtaining aspectral response of the distillate in the pipeline using absorptionspectroscopy with a near infrared analyzer; and correlating the spectralresponse with the measured physical property of the samples. Theforegoing methods apply to any type of distillate fuel, withmeasurements taken upstream or downstream of the injection valve.

EXAMPLES

In the following examples, efforts have been made to ensure accuracywith respect to numbers (e.g., amounts, temperature, etc.) but someerrors and deviations should be accounted for. The following examplesare put forth so as to provide those of ordinary skill in the art with acomplete disclosure and description of how the methods claimed hereinare made and evaluated, and are intended to be purely exemplary of theinvention and are not intended to limit the scope of what the inventorsregard as their invention.

Example 1: Layout of Process Components

The relative locations of the sampling, measuring and injection stepsand systems is a matter of practical convenience. In a particularembodiment, they are located in close proximity to one another. Forexample, the sampling, measuring and injection systems can be housed ona discreet, permanently mounted skid or platform.

Alternatively, the sampling, measuring and injection steps and systemsare located in different locations. For example, the sampling andmeasuring steps can occur at any location upstream of the injection.Furthermore, the injection step can occur either at a single location orat multiple locations. Referring to FIG. 1 , there can be seen adistillate line 1 originating from a distillate source 2, and ultimatelyflowing to the distillate destination 3. A distillate flow meter 4 isalso present on the distillate line for determining the rate ofdistillate through distillate line 1.

FIG. 1 further depicts a biodiesel line 5 in fluid communication withdistillation line 1, originating from a biodiesel source 6. Biodieselline 5 enters the system through biodiesel pump 7 which deliversbiodiesel at a constant pressure to control valve 8 and eventually tobiodiesel junction 9. A biodiesel flow meter 10 is also present onbiodiesel line for determining the flow rate of biodiesel throughbiodiesel line 5.

In a preferred embodiment, a sample of distillate is periodicallywithdrawn from distillate line 1 through sample line 11 at samplejunction 12, or sample line 13 at sample junction 14, or both. Thesample of distillate is routed to a sample valve 15 through the actionof sample pump 16, and subsequently conditioned in sample conditioner 17before delivery and analysis in extracted sample analyzer 18. After thesample is analyzed, the sample is preferably returned to distillate line1 through sample return line 19 and sample return junction 20.

As an alternative to the sample withdrawal procedure described in thepreceding paragraph, sample probes 21 and/or 22 can be installed ondistillate line 1 for periodically analyzing the distillate line usingsample probe analyzer 23.

The entire system, except for the rate of flow through distillate line1, is under the control of IPU 24. IPU 24 is in informationalcommunication with distillate flow meter 4, biodiesel flow meter 10,biodiesel control valve 8, sample valve 15, extracted sample analyzer18, and sample probe analyzer 23. In practice, IPU 24 periodicallyactuates valve 15 to deliver a fresh sample of distillate to extractedsample analyzer 18, at a frequency that does not exceed the timerequired to analyze a sample by analyzer 18. Sample analyzer 18determines the biodiesel content in distillate line 1 at sample junction12 and/or 14, and communicates the results of the analysis to IPU 24,which calculates the rate at which biodiesel can be added to thedistillate source to achieve a predetermined biodiesel content, based onthe content of biodiesel in the distillate stream and the distillateflow rate obtained from distillate flow meter 4, and adjusts biodieselcontrol valve 8 to cause biodiesel to be injected through biodieseljunction 9 at the flow rate calculated by IPU 24.

As an alternative to the sample extraction method described in thepreceding paragraph, CPU 24 can receive the biodiesel content of thedistillate stream through sample probes 21 and/or 22 located upstreamand/or downstream of biodiesel junction 9, based on data communicated bysample probe analyzer 23.

IPU 24 can base its biodiesel flow rate calculation on the biodieselcontent of the distillate stream either upstream of biodiesel junction9, or downstream of biodiesel junction 9 using a feedback controlmechanism. In a preferred embodiment, IPU 24 bases its calculation onthe biodiesel content of the distillate stream 1 upstream of biodieseljunction 9, and it also performs an analysis of the biodiesel content ofdistillate stream 1 downstream of biodiesel junction 9, but only forquality control and reporting purposes.

Example 2: Physical Property Calculations Biodiesel Content

The biodiesel content of the distillate stream can be measured using midinfra-red spectroscopy according to ASTM method D7371 or D7861, whenblending into a diesel stream. These methods can be readily adapted tothe analysis of biodiesel content in other distillate streams such asheating oil or kerosene by methods well known to workers skilled in theart.

In method D7371, a sample of diesel fuel, biodiesel, or biodiesel blendis introduced into a liquid attenuated total reflectance (ATR) samplecell. A beam of infrared light is imaged through the sample onto adetector, and the detector response is determined. Wavelengths of theabsorption spectrum that correlate highly with biodiesel orinterferences are selected for analysis. A multivariate mathematicalanalysis converts the detector; response for the selected areas of thespectrum from an unknown to a concentration of biodiesel. The testmethod preferably uses Fourier transform mid-IR spectrometer with an ATRsample cell. The absorption spectrum is used to calculate a partialleast square (PLS) calibration algorithm.

In method D7861-14, a sample of diesel fuel or biodiesel blend (BXX) isplaced onto a HATR sample crystal. Infrared light is imaged through thesample, then through the LVF and finally onto a detector array. The LVFseparates the infrared light into specific wavelengths so that theresponse of the detector array generates an infrared spectrum. Spectralcorrections are performed to eliminate interferences caused by dieseland bio-diesel variations. A wavelength region of the absorptionspectrum that correlates highly with biodiesel is selected for analysis.The area of the selected region is determined. A calibration curveconverts the selected area of an unknown sample to a concentration ofbiodiesel. The test method preferably uses a LVF array basedmid-infrared spectrometer with an HATR crystal. The absorption spectrumis used to calculate a calibration curve.

Density

A preferred method of measuring the density of a distillate stream isreported as ASTM standard method 4052, conducted at 15° C., using asuitable commercially available density measuring device. A particularlysuitable range of density for the distillate stream in this application,when measured according to the foregoing method, is from 800 to 876kg/m3. Alternatively, or in addition, density can be measured in termsof specific gravity or its corollary, API gravity, where the specificgravity of the distillate stream is preferably from 0.800 to 0.876, andthe API gravity of the distillate stream is preferably from 45.4 to30.0. API gravity and specific gravity are related according to thefollowing formulae:

API Gravity at 60° F.=(141.5/SG)−131.5

Specific Gravity at 60° F.=141.5/(API Gravity+131.5)

The measurement of density according to this invention gives rise toseveral distinct embodiments. In one embodiment, the density of fluidflowing through a pipeline is continually measured, and the biodiesel isinjected into the fuel when the density of the fluid corresponds to thedensity of distillate, but only when the density of the fluidcorresponds to the density of distillate, and not when the fluidcorresponds to the density of a non-distillate fuel.

Example 3: Biodiesel Injection by Two Valve System, and AutonomousControl

Significantly, the injection unit described in any of the foregoingembodiments may comprise two valves. One valve is an on/off valvelocated between the distillate stream and the biodiesel stream. Thisvalve can prevent distillate from entering the biodiesel injection unit.The second valve is a modulating valve that controls the flow ofbiodiesel towards the first valve. The second valve controls the rate offlow of biodiesel by modulating both the pressure of the biodieselstream passing through the valve as well as the size of the orificethrough which the biodiesel stream flows. The modulating valve and/orthe on/off valve may be under the control of a process control unit,which varies the blend ratio to attain a desired biodiesel content,based on the biodiesel content of distillate entering the biodieselinjection unit and the desired biodiesel content of the blendeddistillate. A biodiesel addition rate may then be calculated based uponthe blend ratio and the rate of flow in the distillate stream, and themodulating valve may be opened or closed to allow biodiesel addition atthe rate thus calculated. The valves may also be under the control ofone or more remote information processing units.

Example 4: Databases and Information Processing Unit

Additionally, any of the foregoing embodiments may comprise one or moreinformational databases and an information processing unit (IPU). Inoperation, the IPU retrieves allowable blending parameters (i.e.biodiesel limits) from the informational database and, based on thebiodiesel content of the distillate stream, calculates the blend ratioand/or blend rate based upon the relevant blending parameters. As usedthroughout the present application, the term “retrieve” includes bothretrieving data and receiving data from another source.

The IPU may also process various results of the blending operation andstore the results on the informational database. For example, the IPUcan transmit to the database for recording the upstream physicalproperties of the distillate stream, the downstream physical propertiesof the distillate stream, or the physical properties of the biodieselstream, and can associate such properties with discreet time points orsegments. Such physical properties include, for example, density,volatility, temperature and flow rate.

In other embodiments, the IPU receives or retrieves data from an IPUunder the control of a different entity. Thus, for example, the pipelineoperator may periodically measure the flow rate, density or temperatureof distillate flowing through the pipeline, and transmit (or makeaccessible) such information to the operator of the biodiesel injectionunit for use in the IPU.

Example 5: Adjustability of Blend Rates

The distillate stream of the foregoing embodiments may have a distillateflow rate that does not vary over time, and therefore, the blend ratecan be calculated based upon a pre-set distillate flow rate.Alternatively, the distillate stream may have a distillate flow ratethat varies over time, and therefore, utilization of the invention willfurther comprise periodically determining the distillate flow ratethrough the pipeline, and periodically recalculating the biodiesel blendrate based upon the distillate flow rate and a calculated blend ratio.Specifically, the systems of the present invention may further compriseone or more IPUs in informational communication with upstream biodieselcontent sensors, logically programmed to calculate a blend ratio andblend rate based upon the biodiesel content and volumetric flow rate ofsaid distillate stream, and for communicating said calculated blendratio and calculated blend rate to said biodiesel injection unit;wherein said biodiesel injection unit periodically receives saidcalculated blend ratio and calculated blend rate from said one or moreIPUs, and adjusts the actual blend ratio and actual blend rate tocoincide with said calculated blend ratio and calculated blend rate.

Example 6: Remote and Local Control

Any of the foregoing data, including the target biodiesel content,biodiesel content measurements, and specific gravity measurements can bestored in a database accessible to a remote location through a dedicatedor Internet connection. Furthermore, any of the data or signals encodingthe data can be transmitted via dedicated or Internet connectionsbetween the components of the system.

The foregoing embodiments of the invention may further include a manualswitch to shut down the system. The manual switch may operate to turnoff an on/off valve that may be located between the distillate andbiodiesel streams. The embodiments of the invention may also include anIDB for storing data accessible to an IPU with access to an Internetconnection.

Example 7: Placement Relative to Pipeline and Storage Facility

The biodiesel injection units described in the foregoing embodiments ofthe invention may be placed on a skid or platform. The invention may belocated anywhere downstream of a distillate source. The invention mayalso be located at a distillate tank farm, either before the distillatestream is introduced to a tank, or after the distillate stream iswithdrawn from the tank. The tank farm may be a terminal distillate tankfarm, an intermediate distillate tank farm, or a combined use tank farm.

Throughout this application, various publications are referenced. Thedisclosures of these publications in their entireties are herebyincorporated by reference into this application in order to more fullydescribe the state of the art to which this invention pertains. It willbe apparent to those skilled in the art that various modifications andvariations can be made in the present invention without departing fromthe scope or spirit of the invention. Other embodiments of the inventionwill be apparent to those skilled in the art from consideration of thespecification and practice of the invention disclosed herein. It isintended that the specification and examples be considered as exemplaryonly, with a true scope and spirit of the invention being indicated bythe following claims.

1. An automated method of blending biodiesel into a distillate streamcomprising: a) providing a distillate stream; b) providing a supply ofbiodiesel having a biodiesel stream flow rate in liquid communicationwith said distillate stream, separated from said distillate stream by aregulating valve; c) providing a maximum biodiesel content for saiddistillate stream; d) periodically measuring an actual biodiesel contentin said distillate stream, either upstream or downstream of saidregulating valve; and g) modulating said regulating valve based on theperiodic measurements to blend biodiesel into said distillate stream soas not to exceed the maximum biodiesel content.
 2. The method of claim1, wherein said actual biodiesel content is obtained by generating aspectral response of said distillate stream using absorptionspectroscopy with a near infrared analyzer, and comparing said spectralresponse to a chemometric dataset specific for said value in saiddistillate stream.
 3. The method of claim 2, wherein said chemometricdataset is built by taking two or more samples of said distillate from adistillate stream; measuring said physical property of the samplesoffline; simultaneously with taking the two or more samples, obtaining aspectral response of the distillate in the distillate stream usingabsorption spectroscopy with a near infrared analyzer; and correlatingthe spectral response with the value of the samples.
 4. The method ofclaim 1, wherein said distillate stream comprises a batch of distillatefuel preceded and succeeded by a batch of non-distillate fuel, furthercomprising ceasing any biodiesel blending as said non-distillate fuelpasses said valve.
 5. The method of claim 1, wherein said distillatestream comprises a batch of diesel fuel preceded or succeeded by a batchof aviation fuel, further comprising establishing a buffer of distillatefuel at an interface between said diesel fuel and said aviation fuel,and ceasing biodiesel blending in said buffer.
 6. (canceled) 7.(canceled)
 8. The method of claim 1 wherein said distillate streamcomprises diesel fuel as defined by ASTM D975 or heating oil as definedby ASTM D396.
 9. (canceled)
 10. (canceled)
 11. The method of claim 1,wherein said measuring step (d) occurs upstream of said valve.
 12. Themethod of claim 1, wherein said measuring step (d) occurs downstream ofsaid valve.
 13. (canceled)
 14. The method of claim 1, wherein saidblending occurs inside a variable fuel transmission pipe that transmitsdiesel fuel and aviation fuel.
 15. (canceled)
 16. The method of claim 1,wherein said biodiesel comprises mono-alkyl esters of fatty acidsderived from vegetable oils, animal fats or both.
 17. (canceled)
 18. Themethod of claim 1, wherein said biodiesel consists essentially ofmono-methyl esters of fatty acids derived from vegetable oils, animalfats or both.
 19. (canceled)
 20. The method of claim 19, wherein theregulating valve is under the control of a first central processingunit.
 21. (canceled)
 22. (canceled)
 23. The method of claim 1, whereinsaid distillate stream flow rate varies over time, and step (g) isperformed based upon the distillate stream flow rate.
 24. (canceled) 25.An automated method of blending biodiesel into a distillate streamcomprising: a) providing a distillate stream; b) providing a supply ofbiodiesel in liquid communication with said distillate stream, separatedfrom said distillate stream by a regulating valve; c) providing amaximum biodiesel content for said distillate stream; d) periodicallymeasuring an actual biodiesel content in said distillate stream, eitherupstream or downstream of said regulating valve; g) modulating saidregulating valve based on the periodic measurements to blend biodieselinto said distillate stream and not exceed the maximum biodieselcontent; wherein the distillate stream is preceded or succeeded by anaviation turbine fuel stream, further comprising: h) providing anindicia of aviation turbine fuel corresponding to a physical property ofaviation turbine fuel, accessible by the central processing unit; i)monitoring the distillate stream for the physical property, andtransmitting the physical property to the central processing unit; andj) executing programmable logic on said central processing unit to: i)compare the physical property with the indicia, and ii) communicate tothe regulating valve to stop blending biodiesel when the physicalproperty matches the indicia.
 26. The method of claim 25, wherein saidindicia are selected from the group consisting of density, pour pointand sulfur content, and combinations thereof.
 27. An automated method ofblending biodiesel into a distillate stream comprising: a) providing adistillate stream; b) providing a supply of biodiesel in liquidcommunication with said distillate stream, separated from saiddistillate stream by a regulating valve; c) providing a maximumbiodiesel content for said distillate stream; d) periodically measuringan actual biodiesel content in said distillate stream, either upstreamor downstream of said regulating valve; g) modulating said regulatingvalve based on the period measurements to blend biodiesel into saiddistillate stream and not exceed the actual biodiesel content; whereinsaid distillate stream comprises a batch of distillate fuel preceded andsucceeded by batches of non-distillate fuel, further comprisingmonitoring said distillate stream for the identity of said batch at saidvalve, and only blending biodiesel into said distillate stream when saidbatch of distillate fuel is passing by said valve.
 28. The method ofclaim 27, wherein the identity of said batch is determined by measuringthe density of the stream.
 29. The method of claim 27, wherein theidentity of said batch is determined by measuring the density of thestream, further comprising providing a range of densities associatedwith distillate fuel, and only blending biodiesel into said distillatestream when said stream falls within the range of specific gravities.30. The method of claim 27, wherein the identity of said batch isdetermined based on a batch code associated with the stream that isflowing past the valve.